This invention generally relates to a self-aligning bearing and oil cap mount primarily for use in a fractional horsepower electric motor or the like, and more particularly to such a mount comprising a spacer, spring, and thrust plate, and oil cap where the structures of these components and the manner in which they function together in combination with a self-aligning bearing provide a reliable, long-life, low cost mount that lends itself to assembly with automated techniques. There are numerous self-aligning bearing structures known in the art to which this invention relates. Examples are disclosed in U.S. Pat. Nos. 2,483,013; 2,739,020; 2,751,265; 2,984,528; 3,013,167; 3,164,422; 3,483,409; 3,573,510; 3,624,434; 3,885,176; 4,409,714; 4,456,845; and 4,523,118. The disclosures of these patents include spacers for locating the rotor shaft; spring means of various types for resiliently supporting the bearings; thrust plates to provide thrust bearing means and resilience; oil slingers for directing lubricating oil from the rotor shaft radially outwardly to an oil wick for circulation to the bearings; and oil catchers for catching lubricating oil and preventing it from flowing to the rotor. There are also various techniques known in the art for mounting oil caps to the end shields. These include welding and various types of fasteners.
The spacer, spring, thrust plate and oil cap mount of this invention, and the manner in which they function together, are unique and have numerous advantages. The spacer is of low cost, one piece, molded construction. It has fingers that grip within annular grooves in the rotor shaft and function to axially locate the rotor shaft with great accuracy. The fingers slide along the shaft for ease of assembly by placing the spacer over the end of the shaft and applying an axial force, yet firmly seat within the locating groove in the shaft to securely hold the spacer in place. It has a thrust surface that runs against a thrust plate to carry the thrust load. Radial grooves in the thrust surface are obstructed at their outer ends to trap oil which lubricates the thrust surface and thrust plate. An oil slinger ring directs lubricating oil from the rotor shaft back to the oil wick for recirculation to the self-aligning bearing. The spacer also has an annular trough that functions as an oil catcher for preventing oil from flowing to the rotor.
The spring of this invention is also of low cost, one piece, molded construction, and includes a central hub having a bearing seat at its outer end for receiving the self-aligning bearing therein. It has a ring portion surrounding the hub, the ring portion having an annular recess that receives the thrust plate and supports the thrust plate in axially spaced relation to the hub so that the thrust plate may flex axially under thrust load. Resilient means such as radial arms extend from the hub to the ring and flex under loading applied by the oil cap. Thus, the spring functions to locate and support the thrust plate and self-aligning bearing. It also functions in conjunction with the thrust plate and other components to resiliently support the bearings in the axial direction with the thrust plate flexing to resiliently absorb thrust loads. There is sufficient clearance between the spring and oil cap to allow the bearing to self-align, but yet the oil cap supports the spring, and hence the bearing, during assembly so that the rotor shaft may be easily inserted through the spring and bearing and precisely align the bearing.
The oil cap mounting of this invention has no separate fasteners for securing the oil cap to the end shield, and provides exceptionally low cost assembly with automated techniques. In accordance with this invention, the oil cap is secured to the end shield by protrusions that extend from the surface of the end shield. The protrusions and end shield are of one piece construction with the protrusions formed by lancing. These protrusions define with the end shield surface a recess for receiving the oil cap. The protrusions are deformed radially inwardly against the side and edge of the oil cap to hold it in place. The oil cap may be assembled to the end shield by automated techniques without regard to its circumferential orientation relative to the end shield. The protrusions accurately locate the oil cap to assure its concentricity with the bearing socket in the end shield regardless of the sequence in which the protrusions are radially deformed during automated assembly. The oil cap surrounds the bearing, spring, thrust plate, and spacer, and functions as an enclosure for oil wick for lubricating the bearing surface. It also functions as a bearing retainer and spring retainer and as a support during assembly as previously noted. An outer oil cap may be mounted to the end shield in the same manner to function as a hub for a motor mount for mounting the motor or as a reservoir for additional lubricant.